package org.apache.lucene.util;

/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/** Represents int[], as a slice (offset + length) into an
 *  existing int[].
 *
 *  @lucene.internal */
public final class IntsRef implements Comparable<IntsRef> {

    public int[] ints;
    public int offset;
    public int length;

    public IntsRef() {
    }

    public IntsRef(int capacity) {
        ints = new int[capacity];
    }

    public IntsRef(int[] ints, int offset, int length) {
        this.ints = ints;
        this.offset = offset;
        this.length = length;
    }

    public IntsRef(IntsRef other) {
        copy(other);
    }

    @Override
    public Object clone() {
        return new IntsRef(this);
    }

    @Override
    public int hashCode() {
        final int prime = 31;
        int result = 0;
        final int end = offset + length;
        for (int i = offset; i < end; i++) {
            result = prime * result + ints[i];
        }
        return result;
    }

    @Override
    public boolean equals(Object other) {
        return this.intsEquals((IntsRef) other);
    }

    public boolean intsEquals(IntsRef other) {
        if (length == other.length) {
            int otherUpto = other.offset;
            final int[] otherInts = other.ints;
            final int end = offset + length;
            for (int upto = offset; upto < end; upto++, otherUpto++) {
                if (ints[upto] != otherInts[otherUpto]) {
                    return false;
                }
            }
            return true;
        } else {
            return false;
        }
    }

    /** Signed int order comparison */
    public int compareTo(IntsRef other) {
        if (this == other)
            return 0;

        final int[] aInts = this.ints;
        int aUpto = this.offset;
        final int[] bInts = other.ints;
        int bUpto = other.offset;

        final int aStop = aUpto + Math.min(this.length, other.length);

        while (aUpto < aStop) {
            int aInt = aInts[aUpto++];
            int bInt = bInts[bUpto++];
            if (aInt > bInt) {
                return 1;
            } else if (aInt < bInt) {
                return -1;
            }
        }

        // One is a prefix of the other, or, they are equal:
        return this.length - other.length;
    }

    public void copy(IntsRef other) {
        if (ints == null) {
            ints = new int[other.length];
        } else {
            ints = ArrayUtil.grow(ints, other.length);
        }
        System.arraycopy(other.ints, other.offset, ints, 0, other.length);
        length = other.length;
        offset = 0;
    }

    public void grow(int newLength) {
        if (ints.length < newLength) {
            ints = ArrayUtil.grow(ints, newLength);
        }
    }

    @Override
    public String toString() {
        StringBuilder sb = new StringBuilder();
        sb.append('[');
        final int end = offset + length;
        for (int i = offset; i < end; i++) {
            if (i > offset) {
                sb.append(' ');
            }
            sb.append(Integer.toHexString(ints[i]));
        }
        sb.append(']');
        return sb.toString();
    }
}
